cmProc2.c: use 'offset' as bump mode coeff. in cmSpecDistExec()

cmProc2.c

         break;
 
       case kBumpSdId:
-        _cmSpecDistBump(p,X1m, p->pva->binCnt, p->thresh);
+        _cmSpecDistBump(p,X1m, p->pva->binCnt, p->offset);
         _cmSpecDistBasicMode(p,X1m,p->pva->binCnt,p->thresh);
         break;